refactor: simplify lobby server architecture and update app metadata

* remove legacy data bridge, RPC, and server bootstrap files
* simplify lobby scene and node hierarchy
* rename lobby UI scene path and update signal handlers
* replace the application icon and configure the boot splash
* add project description and version metadata

project.godot

@@ -11,9 +11,14 @@ config_version=5
 [application]
 
 config/name="Lobby Server"
+config/description="A lobby server to handle starting up a game with given game arguments."
+config/version="0.1.0"
 run/main_scene="uid://b0cqo3qo62y6n"
 config/features=PackedStringArray("4.5", "GL Compatibility")
+boot_splash/bg_color=Color(0, 0, 0, 1)
+boot_splash/image="uid://3buyfmedy0qs"
 config/icon="res://icon.svg"
+boot_splash/minimum_display_time=2500
 
 [autoload]